Rename ra_hir -> hir

crates/hir/src/diagnostics.rs

@@ -0,0 +1,6 @@
+//! FIXME: write short doc here
+pub use hir_def::diagnostics::UnresolvedModule;
+pub use hir_expand::diagnostics::{Diagnostic, DiagnosticSink, DiagnosticSinkBuilder};
+pub use hir_ty::diagnostics::{
+    MismatchedArgCount, MissingFields, MissingMatchArms, MissingOkInTailExpr, NoSuchField,
+};